In vitro cultivation of Ehrlichia ruminantium and development of an attenuated culture-derived vaccine

摘要: Ehrlichia ruminantium, an intracellular gram-negative rickettsia, is the causative agent of heartwater, a tick-borne disease domestic and wild ruminants. It major constraint to livestock production throughout sub-Saharan Africa islands Madagascar, La Reunion, Mauritius Sao Tome. The also present in Caribbean, on French Antillean Guadeloupe Antigua, which infected Amblyomma variegatum ticks were introduced, possibly as early eighteenth century. Research into heartwater was hampered for many years by impossibility obtaining viable E. ruminantium organisms defined genotype free from contamination with mammalian cellular material. A turning point reached when suitable culture system became available. However, first vitro exceptionally fragile, unexplained failures used occur frequently, causing frustrating delays research. work described this thesis has provided important contribution improved vaccine development. chemically completely medium continuous propagation been described. Additional studies revealed that broader repertoire host cells than previously assumed. Propagation unusual cell line led emergence attenuated version Welgevonden stock basis development culture-derived vaccine. Preliminary efficacy indicated sheep fully protected against lethal challenge virulent homologous or any four different heterologous stocks. Future aimed at freeze-dried formulation would greatly improve acceptance live, end user. Effective, reliable control using prevent serious outbreaks could have tremendous positive economic impact small-scale well commercial farmers South Africa.